Posted: 04/03/2017 at 10:11
I had two manhole covers in my last front garden and just stood pots on them, filled with hardy bulbs and pansies for winter and easy maintenance pelargoniums for summer as they don't need much watering.
I would agree with Buttercup about losing the grass altogether and improving the soil by forking in some compost. There are often special offers on large bags of cheap multi purpose compost which would improve the texture of your clay. Then cover with a weed suppressing membrane with cross slits for planting shrubs and then spread gravel to tone with your house bricks or slate chippings if you want a contrast. As long as you go for a large grade they should stay put.
As your soil is alkaline, you could use Verdun's suggestion of a lavender edge but you would need to break up the clay with some fine grit and compost as they need good drainage. Don't like wet feet. You won't be able to grow acid lovers such as rhododendron, azalea and camellia but there are plenty of other shrubs that will love it and give you colour and perfume.
Have a look at mahonia Charity and Winter Beauty - evergreen foliage and scented yellow flowers in winter followed by blue-ish berries in summer; hydrangea paniculata forms - flowers on new season's growth so can be pruned back every spring to encourage new flowering stems; viburnum Bodnantense Dawn - scented pink flowers thru winter. For ground cover, have a look at forms of hardy geranium - lots of flower colours plus different forms and colours of foliage. You just need to cut them back after flowering to encourage fresh new foliage and maybe more flowers. Bees love them.
The RHS website has a plant search facility that lets you enter soil type, aspect etc and then suggests suitable plants but the most important thing to do is to improve the soil first so whatever you do choose will thrive with little after care once planted.